Overview
EN ISO 5459:2024 - Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum systems (ISO 5459:2024) is the third-edition international/CEN standard that defines terminology, rules and methodology for indicating and understanding datums and datum systems in technical product documentation. Published in 2024 and endorsed as EN ISO 5459:2024, it replaces the 2011 edition and updates graphical symbols, rules, and guidance to support consistent interpretation of geometrical tolerancing in engineering drawings and CAD documentation.
Key topics and requirements
- Scope and terminology: Clear definitions of datums, single datums, common datums and datum systems to standardize language in GPS and geometric tolerancing.
- Graphical language: Standard symbols and rules for datum feature indicators, datum feature identifiers, datum targets, and datum coordinate system indicators used on drawings.
- Specification operator: Defines the specification operator (per ISO 17450-2) used to establish a datum or datum system. (Note: the verification operator - how a datum is verified physically or mathematically - can take different forms and is outside this document’s scope.)
- Rules and methodology: Prescribed rules for indicating datums, datum sequencing, and the meaning of datum-related symbols to ensure unambiguous documentation and interpretation.
- Filtration and association: Treatment of filtration and association elements that affect how datum features are derived from measured surface data.
- Annexes with guidance: Normative and informative annexes provide association rules, invariance classes, worked examples, filtration guidance (including when nominal datum features are planar), and linkage to the GPS matrix model.
- Updates from 2011: Revised symbols, added new definitions, new Clause on specification operators, and expanded examples and rules.
Applications and users
EN ISO 5459:2024 is essential for anyone involved in geometric tolerancing, product documentation and verification, including:
- Design and mechanical engineers applying GD&T on drawings and CAD models
- Draftsmen and technical illustrators preparing producible documentation
- Metrology and quality engineers specifying and verifying datums during inspection
- Manufacturing and assembly engineers defining functional datum systems for production
- Standards bodies, trainers and consultants developing GPS procedures and tooling
Practical uses include unambiguous datum specification on engineering drawings, consistent datum interpretation across design-to-manufacture workflows, and guidance for developing inspection strategies and measurement software.
Related standards
- ISO 17450-2 - Specification and verification operators (specification operator referenced)
- ISO 2692 - Maximum and least material requirements for datums (detailed rules)
- ISO/TC 213 work on GPS and dimensional metrology (committee responsible)
Keywords: EN ISO 5459:2024, ISO 5459:2024, datums, datum systems, geometrical tolerancing, GPS, datum feature indicator, specification operator, technical product documentation.
